1. Field of the Invention
The present invention relates generally to modular I/O electrical assemblies and more particularly to methods and devices for preventing the mismatched mating of elements of electrical assemblies used to configure the I/O assembly.
2. Description of the Prior Art
It is known to assemble I/O devices into cabinetry and to connect same to its power and signal sources by connections made inside a cabinet with the cabinet then being connected into a unified process control system. As an example, U.S. Pat. No. 3,942,077 to Powers, U.S. Pat. No. 4,152,750 to Bremenour et. al., U.S. Pat. No. 4,334,261 to Gonzales and U.S. Pat. No. 5,423,697 to MacGregor all teach various aspects of such systems.
Furthermore, some known prior art I/O assemblies even have markings on each element of these assemblies to help the assembler in making a proper assembly of an I/O unit to its properly matched signal and power source. Nevertheless, there were still improperly made connections which caused these units to be damaged when they were powered up in a mismatched manner. Thus a device and method was required which would physically prevent the joining of mismatched I/O units to improper signal and power sources.